Clinical Data
The positive CHMP opinion is based on results from the TERRAIN study, which enrolled 375 patients in North America and Europe with metastatic prostate cancer whose disease progressed despite treatment with a luteinizing hormone-releasing hormone (LHRH) analogue therapy or following surgical castration. The trial showed statistically significant progression free survival (PFS) improvement with enzalutamide versus bicalutamide [median PFS 15.7 months vs 5.8 months, HR = 0.44 (95% CI: 0.34, 0.57), p < 0.0001].The median time on treatment in the TERRAIN trial was 11.7 months in the enzalutamide group versus 5.8 months in the bicalutamide group. Grade 3 or higher cardiac adverse events were reported in 5.5% of enzalutamide-treated patients versus 2.1% of bicalutamide-treated patients; the higher rate in the enzalutamide group may be partly due to the twice longer duration of treatment in that group. Two seizures were reported in the enzalutamide group and one in the bicalutamide group. The most common side effects occurring during treatment and more common in the enzalutamide-treated versus bicalutamide-treated patients included fatigue, hot flush, hypertension, diarrhea, weight decreased and pain in extremity. These results were published in Lancet Oncology in January 2016.